After _____ homework, he goes to bed. [ ]
A. doing
B. do
C. does
D. to do
答案：A
It was announced that only when the fire was under control _______ permitted to return to their homes.
A．would villagers be
B．villagers would be
C．should villagers be
D．villagers should be
根据国家标准，机械制图可以得到（）个基本视图。
A.2
B.3
C.4
D.6
